1. Field of the Invention
The present invention relates to rotating magnetic disk drives, and more particularly, to a magnetic disk having efficiently stored wedge repeatable runout (WRRO) compensation values and redundancy information.
2. Description of the Prior Art and Related Information
With reference to FIGS. 6A and 6B, wedge repeatable runout (WRRO) in a disk drive results from imperfections, with respect to a perfect circle, in the location of servo information 80 along a track 82 on a disk surface in the disk drive. During track following, the WRRO imperfections have a detrimental effect on efforts by a head-position servo control loop to cause a transducer head to follow a perfect circle. The WRRO imperfections are relatively static over time and the effects of the RRO may be attenuated by measuring the WRRO and storing resulting WRRO compensation values for later use by the head-position servo loop to compensate for the WRRO.
Accordingly, there exists a need for a technique for efficiently and reliably storing the WRRO compensation values and desirable redundancy information for significantly reducing the effects of WRRO in a disk drive.